Masshole, when was the last time the engine's valve shims were checked or adjusted?
How many miles are on the engine now?
Does the sound follow RPMs - literally - knocking sounds per minute OR is it more like clicking/ticking sounds per second? It's often hard to tell the difference but if you are able to isolate the sound pattern - by the single engine revolution or is it multiple times per engine revolution? The difference of course is valve train or crankshaft. If you are able to / willing to run the engine sitting there, you can use the old screwdriver-to-ear-stethoscope and try to pin-point where you hear it loudest - up in the head, down in the case and this may provide you with a better idea of what's up or down as it were.
The burning oil regularly could be rings but it may also be simple valve stem seals. Mileage on the odo would be a good indicator.
I guess, it needs to be opened up, one way or another since it's clearly engine and not transmission or simple bearings etc. Just would be nice to be expecting a specific area so at minimum, you could be prepared with parts or services needed.